Perhaps most important to being a Jedi master is the ability to maintain a calm demeanor and remain aware of one’s feelings at all times. It is written into the code and exemplified by some of the most revered Jedi masters. Those that fell one step short, like Ahsoka Tano or Anakin Skywalker, did so not because of their deficiencies, but out of a struggle with their emotions.
Mantis is the primary example of the control a Jedi is expected to possess. She can tap into emotions to the point of inheriting or manipulating those of others, even from afar. And while she may be lacking in combat, Mantis can put people directly asleep in mere seconds. Jedi are always attuned to what is happening around them and so is Mantis.
At the same time, she has displayed a great level of heroism as well, warning the Guardians of Ego’s evil plan or vaulting herself head-first into battle against Thanos with every odd pointing against her. She certainly lacks a Jedi’s maturity and can be far too easily controlled, but her heart is in the right place, and her emotional magnitude would likely make her incredibly strong with the force as well.